Expected results: health below 10 hearts should remain below ten hearts after health boost wears off

Observed results: health resets to 10 hearts after health boost runs out when it should have stayed less than 10

Steps to reproduce 

1 create commandblock with command 

/effect @a health_boost 9 9 on impulse and with a button

2 enter survival and press button

3 take damage such that your health is below 10 hearts 

4 wait for health boost to run out

5 observe health returns to 10 Hearst instead of its original value which is below 10 heart

I'm making a map where players armor effects how much health they have and right now they could repeatedly equip and dequip their armor to survive anything indefinitely by resetting their health which I would argue is not proper behavior